hi i was wondering if traing chest twice a week would be over doing it? Ive done this a few times and feel fine but I normally only train it once a week.
Most muscle groups can be trained twice per week with a few days of rest in between, less for smaller muscle groups. Younger trainees may be able to do 3 days per week, assuming you aren't talking about some 20-set chest bonanza. We would probably need to see what your actual workout is before someone can give you a clear answer.
Honestly when I do incline flys and cable crossovers on the same day I occasionally get minor tendinitis in my shoulders.
I'd try going with Dips (heavy 4x6) and medicine ball pushups (3x15-20) instead of that second day.